By Yuko Zhuo
You walk into a room and see everybody on the last cigarette of their pack. What percent of these people are addicted because they chose to? No one chooses to be addicted. However, some people are more susceptible because of the genes they inherit.
A single gene does not cause addiction, addiction is influenced by variations in many genes and environmental factors. One example would be genes responsible for how rapidly nicotine is metabolized in the individual. In a nutshell, if any or all of the genes responsible for the metabolism of nicotine (CYP2A6 and CYP2D6) mutate to a form that enhances metabolism, the chances of continuing smoking and becoming addicted would increase. The reason for this is that a high nicotine metabolism would be able to control the nicotine in the person's body. Another example would be variants of the dopamine receptor genes (DRD1, DRD2, DRD4, and DRD5). Research has proven that the dopamine system has a crucial role in nicotine’s rewarding effects. So, in this case, variants with reduced dopamine receptor expression may increase the chances of becoming a young smoker and fewer successful attempts at quitting. The reason for this may be that individuals with reduced dopamine receptors may compensate for this deficiency by using nicotine to increase brain dopamine levels.
To add on, in a study, where a team of scientists examined earlier studies and their study of 1,000 New Zealanders from birth to age 38, they found that participants who had the “addiction gene” were more likely to smoke daily as teenagers and then progress to smoking heavily (a pack a day or more). Furthermore, among the teens who tried cigarettes, those with “addiction genes” were 24% more likely to become daily smokers by age 15 and 43% more likely to become pack-a-day smokers by age 18.
In another study, researchers discovered that an individual’s genotype may influence several aspects of smoking behavior. For example, genetic factors account for 40–75% of smoking initiation, 70–80% of smoking maintenance, 50% of cessation success, and 30–50% of the risk of withdrawal symptoms.
To conclude, if we can use the knowledge that genes and the urge to smoke are associated, we can work to create therapies or treatments for those who want to quit but cannot. What's more, if an individual knows they have genes that make them more susceptible to smoking, they can use the information to make intelligent decisions to keep their body healthy.
References:
Learn Genetics. (n.d.). Genes and Addiction. Learn.genetics.utah.edu. https://learn.genetics.utah.edu/content/addiction/genes
Davies, G. E., & Soundy, T. J. (2009). The genetics of smoking and nicotine addiction. South Dakota medicine : the journal of the South Dakota State Medical Association, Spec No, 43–49.
Quaak, M., van Schayck, C. P., Knaapen, A. M., & van Schooten, F. J. (2009). Genetic variation as a predictor of smoking cessation success. A promising preventive and intervention tool for chronic respiratory diseases? European Respiratory Journal, 33(3), 468–480. https://doi.org/10.1183/09031936.00056908
Duke Today. (2013, March 27). Genetics Might Determine Which Smokers Get Hooked. Duke Today. https://today.duke.edu/2013/03/smokegenes#:~:text=Genetic%20risk%20was%20related%20to